Strengths and limitations
Our meta-analysis had several strengths. This study included primarily
high quality RCTs providing the highest protection against bias, used
the GRADE approach to assess the overall certainty of evidence. The
study also had several limitations. Firstly, we restricted the inclusion
of studies in English and Chinese, which could have led to missing of
some relevant trials. Secondly, we observed statistically significant
heterogeneity across studies. Such heterogeneity might preclude pooling
of some intervention effects, so caution should be exercised when
interpreting the results. Thirdly, due to insufficient data, we were
unable to conduct subgroup analysis for birthweight and ethnicities.
Fourthly, because of insufficient RCT for peanut oil and liquid
petroleum jelly, so the interpretation of results should be cautious.